The present invention relates to an instrument for applying a liquid such as a hair dye liquid.
Heretofore, as shown in FIGS. 7 and 8, conventional hair dyeing instruments often incorporate an inner shaft reservoir for a hair dye liquid (not shown in the figure) that is housed in the interior of an outer shaft 2 so that it can be freely shifted in the axial direction. Between the inner shaft 1 and the brush 3 fixed at the front end of the outer shaft 2, a valve 4 is interposed allowing the inner shaft 1 to advance against the outer shaft 2 by pressing forward a knock shaft 5 disposed at the rear of the inner shaft 1. The valve 4 is opened so as to supply the hair dye liquid to the brush 3 from the inner shaft 1.
In liquid applicators of similar structure, in order to prevent the liquid from being unwillingly discharged in cases where the knock shaft 5 is accidentally knocked by dropping the applicator, as shown in the above-mentioned figures, means are adopted such that a projection 7 is provided at the inner edge portion of the opening of the tail plug 6 engaged on the rear end of the outer shaft 2. A longitudinal groove 8 in the axial direction and a transverse groove 9 in the circumferential direction into which the projection 7 can be fitted are provided on the outer surface portion of the knock shaft 5. When in use, by positioning the projection in the longitudinal groove, knocking can be done. When not in use, by rotating the knock shaft 5 so as to position the projection in the transverse groove 9, knocking is prevented.
However, the inner shaft 1 holding a liquid therein is so heavy to some degree that it often shifts position by itself on account of the force of inertia from its own weight in cases such as falling, etc. without being pressed by the knock shaft 5. Thus, it has been a disadvantageous point that the unwilling discharge of liquid is inevitable. Further, it has also been a shortcoming that since the provision of a longitudinal groove 8 or a transverse groove 9 on the outer surface portion of the knock shaft 5 compromises the external appearance of the instrument. They are undesirable from the viewpoint of design.
The object of the present invention is therefore to provide a liquid applicator that even when the inner shaft 1 has shifted its position by the force of inertia due to its own weight, the unwilling discharge of liquid can be prevented without compromising the external appearance of the instrument.